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NewsWA sets example on fireThere is a reason Western Australia has been relatively untroubled by bushfire, writes Don Spriggins - From the Financial Review(Don Spriggins is the immediate past chairman and a fellow of the Institute of Foresters, WA division.) Western Australia has not suffered a major forest wildfire since 1961. Has this been due to good fortune or are WA forest managers doing something different from the fire protection practices used by their counterparts in eastern Australia? Fire has been a natural feature of WA forests for thousands of years and the bushfire hazard in the south-west of the state is severe. The combination of a hot, dry Mediterranean climate (no rain of any consequence falls from October to May each year), tall forests which shed large quantities of highly flammable material each year and sources of ignition such as lightning or humans, ensures that summer wildfires occur regularly. The coming of European settlers to WA wrought great changes in fire regimes and led to the abandonment of the Aboriginal frequent burning patterns, which had developed over thousands of years. The early era of uncontrolled land clearing and timber harvesting up until the end of World War I was characterised by destructive wildfires, which ravaged previously cutover forest and damaged young regrowth. After the Forest Act was proclaimed in 1918, the first WA foresters set about developing a fire protection system based on rapid suppression and exclusion of fire from the forest. There was also a belief based on their European forestry training that leaf litter should not be burnt but left to rot down and provide a humus layer, as occurs in many European forests. Little were they to know that eucalypt leaves are almost devoid of nutrients, take years to break down and after about five years of accumulation become an extreme fire hazard. The system worked reasonably well for about 20 years, by which time leaf litter built up to high levels (greater than 20 tonnes per hectare) and fires became more and more difficult to put out each year. In January 1961, a cyclone off the north-west coast directed very strong and hot winds over the south-west of WA. A series of lightning strikes to the south of Perth ignited these heavy fuels in the jarrah forest and a fire burnt uncontrolled for several days, destroying the Dwellingup township in the process. Prescribed burning was introduced on a small scale in the 1950s but too little had been burnt by 1961 to make an impact. Following the Dwellingup fire and subsequent royal commission, prescribed burning was introduced on an extensive scale in the mid-1960s. Aerial ignition of the forest under mild weather conditions has been used ever since as a means of ensuring that fuel levels on the forest floor are burnt before they reach 8 tonnes per hectare. This has been found from years of research and experience to be the level above which it is virtually impossible for fire crews to suppress in summer because of the intense heat generated. On average in the jarrah forest, about 1.5 tonnes per hectare of leaf litter and twigs accumulate on the forest floor each year so that in simple terms, the forest needs to be burnt about every five to seven years to give fire crews a reasonable chance of suppressing a fire. The system has been applied successfully over all land tenures, including national parks and nature reserves, with variations made to take into account values, such as rare and endangered fauna and flora. The system is very similar to that which was used by Aborigines in the south-west probably for 30,000 years or more before Europeans arrived. Objections to prescribed burning have come from people in the environmental movement, many of whom have never experienced a wildfire and are unaware of the extreme impact that wildfires can have on all forest values. Perth residents also dislike the smoke haze that sometimes accompanies prescribed burning and have influenced successive governments to place many restrictions on when burning can occur. Recently, the WA government gave an assurance after the Sydney fires that the prescribed burning program would be maintained. It is hoped that this is a real and lasting commitment that will be honoured by successive governments. Some eastern state colleagues may say the methods used in the relatively flat terrain in the south-west of WA are not directly transferable to the forest types and conditions found on the east coast. Certainly there are differences, and it will be harder in some cases but if there is a will, ways will be found to carry out prescribed burning. Before the emergence of environmental objections to burning, the NSW Forests Commission achieved some excellent results in NSW. Return to the News Archive |
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